Zoom optical system, optical device and method for manufacturing the zoom optical system

ABSTRACT

A zoom optical system (ZL) comprises a first lens group (G 1 ) having positive refractive power, a second lens group (G 2 ) having negative refractive power, a third lens group (G 3 ) having positive refractive power, a fourth lens group (G 4 ) having negative refractive power, and a fifth lens group (G 5 ) having positive refractive power that are disposed in order from an object. Upon zooming from a wide angle end state to a telephoto end state, the lens groups are moved along an optical axis to change distances between the lens groups. The fifth lens group (G 5 ) comprises at least one positive lens and at least one negative lens. Certain conditional expressions are satisfied.

TECHNICAL FIELD

The present invention relates to a zoom optical system, an opticaldevice and a method for manufacturing the zoom optical system.

TECHNICAL BACKGROUND

A zoom optical system suitable for photographic cameras, electronicstill cameras, video cameras, and the like has conventionally beenproposed (see, for example, Patent Document 1).

PRIOR ARTS LIST Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-352057(A)

However, conventional zoom optical systems have a problem in that afurther increase in zooming and angle of view would result in anincrease in size and fail to achieve preferable optical performance.

SUMMARY OF THE INVENTION

A zoom optical system according to the present invention comprises afirst lens group having positive refractive power, a second lens grouphaving negative refractive power, a third lens group having positiverefractive power, a fourth lens group having negative refractive power,and a fifth lens group having positive refractive power that aredisposed in order from an object. Upon zooming from a wide angle endstate to a telephoto end state, the lens groups are moved along anoptical axis to change a distance between the first lens group and thesecond lens group, a distance between the second lens group and thethird lens group, a distance between the third lens group and the fourthlens group, and a distance between the fourth lens group and the fifthlens group. The fifth lens group comprises at least one positive lensand at least one negative lens. The following expressions are satisfied:0.80<(−f4)/f5w<2.50FNw<3.50

where,

f4 denotes a focal length of the fourth lens group,

f5w denotes a composite focal length of an optical system on an imageside including the fifth lens group in the wide angle end state, and

FNw denotes an F number of the whole system in the wide angle end state.

A method for manufacturing a zoom optical system according to thepresent invention is a method for manufacturing a zoom optical systemcomprising a first lens group having positive refractive power, a secondlens group having negative refractive power, a third lens group havingpositive refractive power, a fourth lens group having negativerefractive power, and a fifth lens group having positive refractivepower that are disposed in order from an object. The method formanufacturing a zoom optical system comprises: upon zooming from a wideangle end state to a telephoto end state, arranging the lens groups soas to move along an optical axis to change a distance between the firstlens group and the second lens group, a distance between the second lensgroup and the third lens group, a distance between the third lens groupand the fourth lens group, and a distance between the fourth lens groupand the fifth lens group; and arranging at least one positive lens andat least one negative lens in the fifth lens group, wherein thefollowing expressions are satisfied:0.80<(−f4)/f5w<2.50FNw<3.50

where,

f4 denotes a focal length of the fourth lens group,

f5w denotes a composite focal length of an optical system on an imageside including the fifth lens group in the wide angle end state, and

FNw denotes an F number of the whole system in the wide angle end state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram illustrating a lens configuration ofa zoom optical system according to Example 1.

FIGS. 2A and 2B are various aberration graphs of the zoom optical systemin a wide angle end state according to Example 1, FIG. 2A being avarious aberration graph in a focusing-on-infinity state, FIG. 2B beinga lateral aberration graph in the focusing-on-infinity state with imageshake correction performed.

FIGS. 3A and 3B are various aberration graphs of the zoom optical systemin an intermediate focal length state according to Example 1, FIG. 3Abeing a various aberration graph in the focusing-on-infinity state, FIG.3B being a lateral aberration graph in the focusing-on-infinity statewith image shake correction performed.

FIGS. 4A and 4B are various aberration graphs of the zoom optical systemin a telephoto end state according to Example 1, FIG. 4A being a variousaberration graph in the focusing-on-infinity state, FIG. 4B being alateral aberration graph in the focusing-on-infinity state with imageshake correction performed.

FIGS. 5A-5C are various aberration graphs of the zoom optical system ina focusing-on-a-short-distant-object state according to Example 1, FIG.5A being a various aberration graph in a wide angle end state, FIG. 5Bbeing a various aberration graph in an intermediate focal length state,FIG. 5C being a various aberration graph in a telephoto end state.

FIG. 6 is a cross-sectional diagram illustrating a lens configuration ofa zoom optical system according to Example 2.

FIGS. 7A and 7B are various aberration graphs of the zoom optical systemin a wide angle end state according to Example 2, FIG. 7A being avarious aberration graph in a focusing-on-infinity state, FIG. 7B beinga lateral aberration graph in the focusing-on-infinity state with imageshake correction performed.

FIGS. 8A and 8B are various aberration graphs of the zoom optical systemin an intermediate focal length state according to Example 2, FIG. 8Abeing a various aberration graph in the focusing-on-infinity state, FIG.8B being a lateral aberration graph in the focusing-on-infinity statewith image shake correction performed.

FIGS. 9A and 9B are various aberration graphs of the zoom optical systemin a telephoto end state according to Example 2, FIG. 9A being a variousaberration graph in the focusing-on-infinity state, FIG. 9B being alateral aberration graph in the focusing-on-infinity state with imageshake correction performed.

FIGS. 10A-10C are various aberration graphs of the zoom optical systemin a focusing-on-a-short-distant-object state according to Example 2,FIG. 10A being a various aberration graph in a wide angle end state,FIG. 10B being a various aberration graph in an intermediate focallength state, FIG. 10C being a various aberration graph in a telephotoend state.

FIG. 11 is a cross-sectional diagram illustrating a lens configurationof a zoom optical system according to Example 3.

FIGS. 12A and 12B are various aberration graphs of the zoom opticalsystem in a wide angle end state according to Example 3, FIG. 12A beinga various aberration graph in a focusing-on-infinity state, FIG. 12Bbeing a lateral aberration graph in the focusing-on-infinity state withimage shake correction performed.

FIGS. 13A and 13B are various aberration graphs of the zoom opticalsystem in an intermediate focal length state according to Example 3,FIG. 13A being a various aberration graph in the focusing-on-infinitystate, FIG. 13B being a lateral aberration graph in thefocusing-on-infinity state with image shake correction performed.

FIGS. 14A and 14B are various aberration graphs of the zoom opticalsystem in a telephoto end state according to Example 3, FIG. 14A being avarious aberration graph in the focusing-on-infinity state, FIG. 14Bbeing a lateral aberration graph in the focusing-on-infinity state withimage shake correction performed.

FIGS. 15A-15C are various aberration graphs of the zoom optical systemin a focusing-on-a-short-distant-object state according to Example 3,FIG. 15A being a various aberration graph in a wide angle end state,FIG. 15B being a various aberration graph in an intermediate focallength state, FIG. 15C being a various aberration graph in a telephotoend state.

FIG. 16 is a cross-sectional view of a camera including the zoom opticalsystem.

FIG. 17 is a flowchart for describing a method for manufacturing thezoom optical system.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention are described below withreference to the drawings. As illustrated in FIG. 1, a zoom opticalsystem ZL according to the present embodiment has a configurationincluding: a first lens group G1 having positive refractive power; asecond lens group G2 having negative refractive power; a third lensgroup G3 having positive refractive power; a fourth lens group 4G havingnegative refractive power; and a fifth lens group G5 having positiverefractive power that are disposed in order from an object. In the zoomoptical system ZL, upon zooming from a wide angle end state to atelephoto end state, the lens groups G1 to G5 are moved along theoptical axis to change a distance between the first lens group G1 andthe second lens group G2, a distance between the second lens group G2and the third lens group G3, a distance between the third lens group G3and the fourth lens group G4, and a distance between the fourth lensgroup G4 and the fifth lens group G5. In the zoom optical system ZL, thefifth lens group G5 includes at least one positive lens and at least onenegative lens. With such a configuration, a lens with a high F numberand excellent optical performance can be achieved.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (1).0.80<(−f4)/f5w<2.50  (1)

where,

f4 denotes a focal length of the fourth lens group G4, and

f5w denotes a composite focal length of an optical system on an imageside including the fifth lens group G5 in the wide angle end state.

The conditional expression (1) is for setting a ratio of the focallength of the fourth lens group G4 and the composite focal length of theoptical system on the image side including the fifth lens group G5 inthe wide angle end state. f5w in a five-group configuration as inExample 1 and Example 2 described below is the focal length of the fifthlens group G5, and f5w in a six-group configuration as in Example 3 isthe composite focal length of the fifth lens group G5 and the sixth lensgroup G6 in the wide angle end state. Variation of aberrations uponzooming can be reduced while achieving an increase in zooming, size ofaperture, and angle of view when the conditional expression (1) issatisfied. Furthermore, the outer diameters of the third lens group G3and the fourth lens group G4 can be made small, thereby achieving asmall size of the barrel. A value higher than the upper limit value ofthe conditional expression (1) unfavorably leads to excessively largerefractive power of the fifth lens group G5 and deteriorated imagingperformance due to manufacturing errors, that is, excessively largedecentering coma aberrations and decentering image surface collapse. Toguarantee the effects of the conditional expression (1), the upper limitvalue of the conditional expression (1) is preferably set to be 2.00. Tofurther guarantee the effects of the conditional expression (1), theupper limit value of the conditional expression (1) is preferably set tobe 1.40. To further guarantee the effects of the conditional expression(1), the upper limit value of the conditional expression (1) ispreferably set to be 1.10. A value lower than the lower limit value ofthe conditional expression (1) leads to excessively large refractivepower of the fourth lens group G4 and excessively large variation ofcoma aberrations upon zooming. This also unfavorably leads to anincrease in the diameter of the third lens group G3, an excessivelylarge increase in the product diameter and in high-order sphericalaberrations, which renders such aberrations difficult to correct. Toguarantee the effects of the conditional expression (1), the lower limitvalue of the conditional expression (1) is preferably set to be 0.84. Tofurther guarantee the effects of the conditional expression (1), thelower limit value of the conditional expression (1) is preferably set tobe 0.88.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (2).FNw<3.50  (2)

where,

FNw denotes an F number of the whole system in the wide angle end state.

The conditional expression (2) is for setting the F number of the wholesystem of the zoom optical system ZL according to the present embodimentin the wide angle end state. A larger aperture can be achieved andspherical aberrations and the like can be successfully corrected whenthe conditional expression (2) is satisfied. To guarantee the effects ofthe conditional expression (2), the upper limit value of the conditionalexpression (2) is preferably set to be 3.30. To further guarantee theeffects of the conditional expression (2), the upper limit value of theconditional expression (2) is preferably set to be 3.10. To furtherguarantee the effects of the conditional expression (2), the upper limitvalue of the conditional expression (2) is preferably set to be 2.90.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expressions (3) and (4).0.30<N5n−N5p  (3)1.85<N5n  (4)

where,

N5n denotes an average refractive index with respect to the d line ofall the negative lens media in the fifth lens group G5, and

N5p denotes an average refractive index with respect to the d line ofall the positive lens media in the fifth lens group G5.

The conditional expressions (3) and (4) are for setting a refractiveindex of a lens medium in the fifth lens group G5. The curvature of thelens surface in the fifth lens group G5 can be reduced and high-orderspherical aberrations, coma aberrations, and curvature of field, whichwould cause a problem in increasing the aperture and angle of view, canbe successfully corrected when the conditional expressions (3) and (4)are satisfied. To guarantee the effects of the conditional expression(3), the lower limit value of the conditional expression (3) ispreferably set to be 0.33. To further guarantee the effects of theconditional expression (3), the lower limit value of the conditionalexpression (3) is preferably set to be 0.35. To guarantee the effects ofthe conditional expression (4), the lower limit value of the conditionalexpression (4) is preferably set to be 1.86. To further guarantee theeffects of the conditional expression (4), the lower limit value of theconditional expression (4) is preferably set to be 1.88.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (5).3.50<ft/fw  (5)

where,

fw denotes a focal length of the whole system in the wide angle endstate, and

ft denotes a focal length of the whole system in the telephoto endstate.

The conditional expression (5) is for setting a ratio of the focallength of the whole system in the telephoto end state and the focallength of the whole system in the wide angle end state, that is, azooming rate. A higher zooming rate can be achieved and sphericalaberrations and coma aberrations can be successfully corrected when theconditional expression (5) is satisfied. To guarantee the effects of theconditional expression (5), the lower limit value of the conditionalexpression (5) is preferably set to be 3.80. To guarantee the effects ofthe conditional expression (5), the lower limit value of the conditionalexpression (5) is preferably set to be 4.00.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (6).FNt<4.50  (6)

where,

FNt denotes an F number of the whole system in the telephoto end state.

The conditional expression (6) is for setting the F number of the wholesystem of the zoom optical system ZL according to the present embodimentin the telephoto end state. A larger aperture can be achieved andspherical aberrations and the like can be successfully corrected whenthe conditional expression (6) is satisfied. To guarantee the effects ofthe conditional expression (6), the upper limit value of the conditionalexpression (6) is preferably set to be 4.40. To further guarantee theeffects of the conditional expression (6), the upper limit value of theconditional expression (6) is preferably set to be 4.30. To furtherguarantee the effects of the conditional expression (6), the upper limitvalue of the conditional expression (6) is preferably set to be 4.20.

In the zoom optical system ZL according to the present embodiment, uponzooming from a wide angle end state to a telephoto end state, the lensgroups are preferably configured to be moved along the optical axis toincrease a distance between the first lens group G1 and the second lensgroup G2, decrease a distance between the second lens group G2 and thethird lens group G3, increase a distance between the third lens group G3and the fourth lens group G4, and decrease a distance between the fourthlens group G4 and the fifth lens group G5. With this configuration, ahigher zooming rate and reduced power (refractive power) of the lensgroups can be achieved and reduction in high-order aberrations anddeteriorated imaging performance in manufacturing can be maintainedsmall.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (7).2.50<f1/f3<4.20  (7)

where,

f1 denotes the focal length of the first lens group G1, and

f3 denotes the focal length of the third lens group G3.

The conditional expression (7) is for setting a ratio of the focallengths of the first lens group G1 and the third lens group G3.Aberrations while achieving an increase in size of aperture and angle ofview can be achieved in a balanced manner when the conditionalexpression (7) is satisfied. A value higher than the upper limit valueof the conditional expression (7) leads to excessively large refractivepower of the third lens group G3, rendering high-order sphericalaberrations and coma aberrations, while achieving an increase in size ofaperture, difficult to correct. Furthermore, this unfavorably leads todeteriorated imaging performance due to manufacturing errors, that is,excessively large decentering coma aberrations and decentering imagesurface collapse. To guarantee the effects of the conditional expression(7), the upper limit value of the conditional expression (7) ispreferably set to be 4.00. To further guarantee the effects of theconditional expression (7), the upper limit value of the conditionalexpression (7) is preferably set to be 3.80. To further guarantee theeffects of the conditional expression (7), the upper limit value of theconditional expression (7) is preferably set to be 3.70. A value lowerthan the lower limit value of the conditional expression (7) leads toexcessively large refractive power of the first lens group G1 andexcessively large variation of curvature of field upon zooming.Furthermore, an increase in angle of view renders high-order curvatureof field difficult to correct. This also unfavorably leads to anincrease in the diameter of the first lens group G1 and an increase inthe product diameter. To guarantee the effects of the conditionalexpression (7), the lower limit value of the conditional expression (7)is preferably set to be 2.80. To further guarantee the effects of theconditional expression (7), the lower limit value of the conditionalexpression (7) is preferably set to be 3.10. To further guarantee theeffects of the conditional expression (7), the lower limit value of theconditional expression (7) is preferably set to be 3.30.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (8).0.25<f2/f4<0.55  (8)

where,

f2 denotes the focal length of the second lens group G2, and

f4 denotes the focal length of the fourth lens group G4.

The conditional expression (8) is for setting a ratio of the focallengths of the second lens group G2 and the fourth lens group G4.Aberrations while achieving an increase in size of aperture and angle ofview can be achieved in a balanced manner when the conditionalexpression (8) is satisfied. A value higher than the upper limit valueof the conditional expression (8) leads to excessively large refractivepower of the fourth lens group G4, rendering high-order sphericalaberrations and coma aberrations, while achieving an increase in size ofaperture, difficult to correct. Furthermore, this unfavorably leads todeteriorated imaging performance due to manufacturing errors, that is,excessively large decentering coma aberrations and decentering imagesurface collapse. To guarantee the effects of the conditional expression(8), the upper limit value of the conditional expression (8) ispreferably set to be 0.50. To further guarantee the effects of theconditional expression (8), the upper limit value of the conditionalexpression (8) is preferably set to be 0.45. To further guarantee theeffects of the conditional expression (8), the upper limit value of theconditional expression (8) is preferably set to be 0.40. A value lowerthan the lower limit value of the conditional expression (8) leads toexcessively large refractive power of the second lens group G2 andexcessively large variation of curvature of field upon zooming.Furthermore, an increase in angle of view renders high-order curvatureof field difficult to correct. This also unfavorably leads to anincrease in the diameter of the first lens group G1 and an increase inthe product diameter. To guarantee the effects of the conditionalexpression (8), the lower limit value of the conditional expression (8)is preferably set to be 0.28. To further guarantee the effects of theconditional expression (8), the lower limit value of the conditionalexpression (8) is preferably set to be 0.30. To further guarantee theeffects of the conditional expression (8), the lower limit value of theconditional expression (8) is preferably set to be 0.33.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (9).1.85<N2max  (9)

where,

N2max denotes a maximum absolute value of the refractive index withrespect to the d line of the lens medium in the second lens group G2.

The conditional expression (9) is for setting a refractive index of alens medium in the second lens group G2. Variation of sphericalaberrations and comma aberrations upon zooming can be reduced when theconditional expression (9) is satisfied. To guarantee the effects of theconditional expression (9), the lower limit value of the conditionalexpression (9) is preferably set to be 1.86. To further guarantee theeffects of the conditional expression (9), the lower limit value of theconditional expression (9) is preferably set to be 1.88.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (10).0.4<fw/f3<1.00  (10)

where,

fw denotes the focal length of the whole system in the wide angle endstate, and

f3 denotes the focal length of the third lens group G3.

The conditional expression (10) is for setting a ratio of the focallength of the whole system of the zoom optical system ZL in the wideangle end state and the focal length of the third lens group G3.Correction of high-order aberrations with an increase in size ofaperture, reduction in variation of aberrations with a higher zoomingrate, and a smaller size of the product can be achieved in a balancedmanner when the conditional expression (10) is satisfied. A value higherthan the upper limit value of the conditional expression (10) leads toexcessively large refractive power of the third lens group G3, renderinghigh-order spherical aberrations and coma aberrations, due to anincrease in size of aperture, difficult to correct. Furthermore, thisunfavorably leads to deteriorated imaging performance due tomanufacturing errors, that is, excessively large decentering comaaberrations and decentering image surface collapse. To guarantee theeffects of the conditional expression (10), the upper limit value of theconditional expression (10) is preferably set to be 0.90. To furtherguarantee the effects of the conditional expression (10), the upperlimit value of the conditional expression (10) is preferably set to be0.80. A value lower than the lower limit value of the conditionalexpression (10) leads to excessively small refractive power of the thirdlens group G3 and fails to guarantee sufficient zooming. As a result, toguarantee sufficient zooming, the refractive power of the first lensgroup G1, the second lens group G2, the fifth lens group G5, and thelike becomes excessively large, which unfavorably leads to excessivelylarge variation of curvature of field upon zooming and excessively largeaberration deterioration and the like in manufacturing due to increasedsensitivity of the fifth lens group G5. To guarantee the effects of theconditional expression (10), the lower limit value of the conditionalexpression (10) is preferably set to be 0.45. To further guarantee theeffects of the conditional expression (10), the lower limit value of theconditional expression (10) is preferably set to be 0.50. To furtherguarantee the effects of the conditional expression (10), the lowerlimit value of the conditional expression (10) is preferably set to be0.60.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (11).0.30<fw/(−f4)<0.80  (11)

where,

fw denotes the focal length of the whole system in the wide angle endstate, and

f4 denotes the focal length of the fourth lens group G4.

The conditional expression (11) is for setting a ratio of the focallength of the whole system of the zoom optical system ZL in the wideangle end state and the focal length of the fourth lens group G4.Correction of high-order aberrations with an increase in size ofaperture, reduction in variation of aberrations with a higher zoomingrate, and a smaller size of the product can be achieved in a balancedmanner when the conditional expression (11) is satisfied. A value higherthan the upper limit value of the conditional expression (11) leads toexcessively large refractive power of the fourth lens group G4,rendering high-order spherical aberrations and coma aberrations, due toan increase in size of aperture, difficult to correct. Furthermore, thisunfavorably leads to deteriorated imaging performance due tomanufacturing errors, that is, excessively large decentering comaaberrations and decentering image surface collapse. To guarantee theeffects of the conditional expression (11), the upper limit value of theconditional expression (11) is preferably set to be 0.70. To furtherguarantee the effects of the conditional expression (11), the upperlimit value of the conditional expression (11) is preferably set to be0.60. A value lower than the lower limit value of the conditionalexpression (11) leads to excessively small refractive power of thefourth lens group G4 and fails to guarantee sufficient zooming. As aresult, to guarantee sufficient zooming, the refractive power of thefirst lens group G1, the second lens group G2, the fifth lens group G5,and the like becomes excessively large, which unfavorably leads toexcessively large variation of curvature of field upon zooming andexcessively large aberration deterioration and the like in manufacturingdue to increased sensitivity of the fifth lens group G5. To guaranteethe effects of the conditional expression (11), the lower limit value ofthe conditional expression (11) is preferably set to be 0.35. To furtherguarantee the effects of the conditional expression (11), the lowerlimit value of the conditional expression (11) is preferably set to be0.38. To further guarantee the effects of the conditional expression(11), the lower limit value of the conditional expression (11) ispreferably set to be 0.42.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (12).2.00<ft/f3<5.00  (12)

where,

ft denotes the focal length of the whole system in the telephoto endstate, and

f3 denotes the focal length of the third lens group G3.

The conditional expression (12) is for setting a ratio of the focallength of the whole system of the zoom optical system ZL in thetelephoto end state and the focal length of the third lens group G3.Correction of high-order aberrations with an increase in size ofaperture, reduction in variation of aberrations with a higher zoomingrate, and a smaller size of the product can be achieved in a balancedmanner when the conditional expression (12) is satisfied. A value higherthan the upper limit value of the conditional expression (12) leads toexcessively large refractive power of the third lens group G3, renderinghigh-order spherical aberrations and coma aberrations, due to anincrease in size of aperture, difficult to correct. Furthermore, thisunfavorably leads to deteriorated imaging performance due tomanufacturing errors, that is, excessively large decentering comaaberrations and decentering image surface collapse. To guarantee theeffects of the conditional expression (12), the upper limit value of theconditional expression (12) is preferably set to be 4.50. To furtherguarantee the effects of the conditional expression (12), the upperlimit value of the conditional expression (12) is preferably set to be4.00. To further guarantee the effects of the conditional expression(12), the upper limit value of the conditional expression (12) ispreferably set to be 3.50. A value lower than the lower limit value ofthe conditional expression (12) leads to excessively small refractivepower of the third lens group G3 and fails to guarantee sufficientzooming. As a result, to guarantee sufficient zooming, the refractivepower of the first lens group G1, the second lens group G2, the fifthlens group G5, and the like becomes excessively large, which unfavorablyleads to excessively large variation of curvature of field upon zoomingand excessively large aberration deterioration and the like inmanufacturing due to increased sensitivity of the fifth lens group G5.To guarantee the effects of the conditional expression (12), the lowerlimit value of the conditional expression (12) is preferably set to be2.40. To further guarantee the effects of the conditional expression(12), the lower limit value of the conditional expression (12) ispreferably set to be 2.60. To further guarantee the effects of theconditional expression (12), the lower limit value of the conditionalexpression (12) is preferably set to be 2.90.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (13).1.50<ft/(−f4)<4.50  (13)

where,

ft denotes the focal length of the whole system in the telephoto endstate, and

f4 denotes the focal length of the fourth lens group G4.

The conditional expression (13) is for setting a ratio of the focallength of the whole system of the zoom optical system ZL in thetelephoto end state and the focal length of the fourth lens group G4.Correction of high-order aberrations with an increase in size ofaperture, reduction in variation of aberrations with a higher zoomingrate, and a smaller size of the product can be achieved in a balancedmanner when the conditional expression (13) is satisfied. A value higherthan the upper limit value of the conditional expression (13) leads toexcessively large refractive power of the fourth lens group G4,rendering high-order spherical aberrations and coma aberrations, due toan increase in size of aperture, difficult to correct. Furthermore, thisunfavorably leads to deteriorated imaging performance due tomanufacturing errors, that is, excessively large decentering comaaberrations and decentering image surface collapse. To guarantee theeffects of the conditional expression (13), the upper limit value of theconditional expression (13) is preferably set to be 4.00. To furtherguarantee the effects of the conditional expression (13), the upperlimit value of the conditional expression (13) is preferably set to be3.50. To further guarantee the effects of the conditional expression(13), the upper limit value of the conditional expression (13) ispreferably set to be 3.00. To further guarantee the effects of theconditional expression (13), the upper limit value of the conditionalexpression (13) is preferably set to be 2.50. A value lower than thelower limit value of the conditional expression (13) leads toexcessively small refractive power of the fourth lens group G4 and failsto guarantee sufficient zooming. As a result, to guarantee sufficientzooming, the refractive power of the first lens group G1, the secondlens group G2, the fifth lens group G5, and the like becomes excessivelylarge, which unfavorably leads to excessively large variation ofcurvature of field upon zooming and excessively large aberrationdeterioration and the like in manufacturing due to increased sensitivityof the fifth lens group G5. To guarantee the effects of the conditionalexpression (13), the lower limit value of the conditional expression(13) is preferably set to be 1.60. To further guarantee the effects ofthe conditional expression (13), the lower limit value of theconditional expression (13) is preferably set to be 1.80. To furtherguarantee the effects of the conditional expression (13), the lowerlimit value of the conditional expression (13) is preferably set to be2.00.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expressions (14) and(15).0.30<N3n−N3p  (14)1.85<N3n  (15)

where,

N3n denotes an average refractive index with respect to the d line ofall the negative lens media in the third lens group G3, and

N3p denotes an average refractive index with respect to the d line ofall the positive lens media in the third lens group G3.

The conditional expressions (14) and (15) are for setting a refractiveindex of a lens medium in the third lens group G3. The curvature of thelens surface in the third lens group G3 can be reduced and high-orderspherical aberrations and coma aberrations, which would cause a problemin increasing the aperture and the zooming rate, as well as variation ofaberrations can be successfully corrected when the conditionalexpressions (14) and (15) are satisfied. To guarantee the effects of theconditional expression (14), the lower limit value of the conditionalexpression (14) is preferably set to be 0.33. To guarantee the effectsof the conditional expression (15), the lower limit value of theconditional expression (15) is preferably set to be 1.88.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (16).25.0°<ωw<60.0°  (16)

where,

ωw denotes a half angle of view in the wide angle end state.

The conditional expression (16) is for setting an optimum value of anangle of view in the wide angle end state. Various aberrations, such asa coma aberration, distortion, and curvature of field, can besuccessfully corrected while guaranteeing a wide angle of view, when theconditional expression (16) is satisfied. To guarantee the effects ofthe conditional expression (16), the upper limit value of theconditional expression (16) is preferably set to be 50.0°. To furtherguarantee the effects of the conditional expression (16), the upperlimit value of the conditional expression (16) is preferably set to be45.0°. To guarantee the effects of the conditional expression (16), thelower limit value of the conditional expression (16) is preferably setto be 30.0°. To further guarantee the effects of the conditionalexpression (16), the lower limit value of the conditional expression(16) is preferably set to be 35.0°.

The zoom optical system ZL according to the present embodimentpreferably satisfies the following conditional expression (17).3.0°<ωt<20.0°  (17)

where,

ωt denotes a half angle of view in the telephoto end state.

The conditional expression (17) is for determining an optimum value ofan angle of view in the telephoto end state. Various aberrations, suchas a coma aberration, distortion, and curvature of field, can besuccessfully corrected, when the conditional expression (17) issatisfied. To guarantee the effects of the conditional expression (17),the upper limit value of the conditional expression (17) is preferablyset to be 15.0°. To further guarantee the effects of the conditionalexpression (17), the upper limit value of the conditional expression(17) is preferably set to be 12.0°. To guarantee the effects of theconditional expression (17), the lower limit value of the conditionalexpression (17) is preferably set to be 5.0°. To further guarantee theeffects of the conditional expression (17), the lower limit value of theconditional expression (17) is preferably set to be 7.0°. To furtherguarantee the effects of the conditional expression (17), the lowerlimit value of the conditional expression (17) is preferably set to be8.0°.

The zoom optical system ZL according to the present embodimentpreferably has at least an aspherical lens surface in the fifth lensgroup G5. With this configuration, high-order spherical aberrations,coma aberrations, and curvature of field can be successfully corrected.

The zoom optical system ZL according to the present embodiment ispreferably configured to perform correction (vibration isolation) on theposition of the image when image shake has occurred by moving at leastsome of the first lens group G1, the second lens group G2, the thirdlens group G3, the fourth lens group G4, and the fifth lens group G5 tohave a displacement component in the direction orthogonal to the opticalaxis. Any one of the lens groups may be moved to have a displacementcomponent in the direction orthogonal to the optical axis, or a part ofthe lenses or lens groups in any one of the lens groups may be moved tohave a displacement component in the direction orthogonal to the opticalaxis.

The zoom optical system ZL according to the present embodiment ispreferably configured to perform correction (vibration isolation) on theposition of the image when image shake has occurred by moving at leastapart of the fourth lens group G4 to have a displacement component inthe direction orthogonal to the optical axis. Making a negative lensgroup with a low beam height, such as the fourth lens group G4, functionas a vibration-proof lens group can achieve a small size of the lensouter diameter. Furthermore, by positioning the vibration-proof lensgroup around halfway between an aperture stop S and an image surface I,a beam change can be reduced while correcting the position of the imagewhen image shake has occurred and variation of aberrations in imageshake correction can also be reduced.

The zoom optical system ZL according to the present embodiment mayperform correction (vibration isolation) on the position of the imagewhen image shake has occurred by moving one of the fourth-A lens groupG4A having negative refractive power and the fourth-B lens group G4Bhaving negative refractive power, which are included in the fourth lensgroup G4, to have a displacement component in the direction orthogonalto the optical axis. With this configuration, various aberrations inpositive refractive power components in the third lens group G3 and thefifth lens group G5 during image surface correction when image shake hasoccurred can be corrected by various aberrations in negative refractivepower components in the lens group included in the fourth lens group G4that is not vibration-proof, resulting in successful correction ofaberrations during image surface correction when image shake hasoccurred.

In the zoom optical system ZL according to the present embodiment, thethird lens group G3 and the fifth lens group G5 preferably move towardthe object upon zooming from the wide angle end state to the telephotoend state with the same movement amount with respect to the imagesurface I. With this configuration, the third lens group G3 and thefifth lens group G5 can be integrated, mutual decentering change can bereduced upon zooming from the wide angle end state to the telephoto endstate, and deterioration of optical performance due to manufacturingerrors can be mitigated.

The zoom optical system ZL according to the present embodiment ispreferably configured to move at least a part of the second lens groupG2 along the optical axis upon focusing on a short distance object. Withthis configuration, variation of spherical aberrations and curvature offield upon focusing can be reduced while achieving a reduced outerdiameter and lighter weight of the focusing groups.

The zoom optical system ZL according to the present embodimentpreferably has at least an aspherical lens surface in the fourth lensgroup G4. With this configuration, high-order spherical aberrations andcoma aberrations can be successfully corrected.

The zoom optical system ZL according to the present embodimentpreferably has at least an aspherical lens surface in the second lensgroup G2. With this configuration, high-order curvature of field andcoma aberrations can be successfully corrected.

In the zoom optical system ZL according to the present embodiment, atleast one optical surface in the lens group closest to the image withrespect to the first lens group G1 is provided with an antireflectionfilm. The antireflection film includes at least one layer with nd of1.30 or less where nd denotes the refractive index with respect to the dline (wavelength λ=587.6 nm). With this configuration, the difference inrefractive index between the layer with a refractive index nd of 1.30 orless and the air can be reduced, resulting in less reflection of lightto achieve an excellent imaging performance with reduced ghosting andflare.

The zoom optical system ZL according to the present embodimentpreferably includes an aperture stop, and the optical surface providedwith the antireflection film is a concave lens surface as seen from theaperture stop. The concave lens surface as seen from the aperture stopamong the optical surfaces in the lens group closest to the image withrespect to the first lens group G1 is likely to cause light reflection.To address this, the antireflection film is provided to the lens surfaceso that ghosting and flare can be effectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the aperture stop is preferably a lenssurface facing the object among the lenses in the first lens group G1.The concave lens surface as seen from the aperture stop among theoptical surfaces in the first lens group G1 is likely to cause lightreflection. To address this, the antireflection film is provided to thelens surface so that ghosting and flare can be effectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the aperture stop is preferably a lenssurface facing the image among the lenses in the first lens group G1.The concave lens surface as seen from the aperture stop among theoptical surfaces in the first lens group G1 is likely to cause lightreflection. To address this, the antireflection film is provided to thelens surface so that ghosting and flare can be effectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the aperture stop is preferably a lenssurface facing the object among the lenses in the lens group closest tothe image. The concave lens surface as seen from the aperture stop amongthe optical surfaces in the lens group closest to the image is likely tocause light reflection. To address this, the antireflection film isprovided to the lens surface so that ghosting and flare can beeffectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the aperture stop is preferably a lenssurface facing the image among the lenses in the lens group closest tothe image. The concave lens surface as seen from the aperture stop amongthe optical surfaces in the lens group closest to the image is likely tocause light reflection. To address this, the antireflection film isprovided to the lens surface so that ghosting and flare can beeffectively reduced.

In the zoom optical system ZL according to the present embodiment, theoptical surface provided with the antireflection film is a concave lenssurface as seen from the image side. The concave lens surface as seenfrom the image side among the optical surfaces in the lens group closestto the image and the first lens group G1 is likely to cause lightreflection. To address this, the antireflection film is provided to thelens surface so that ghosting and flare can be effectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the image side is preferably a lenssurface facing the object among the lenses in the lens group closest tothe image. The concave lens surface as seen from the image side amongthe optical surfaces in the lens group closest to the image is likely tocause light reflection. To address this, the antireflection film isprovided to the lens surface so that ghosting and flare can beeffectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the image side is preferably a lenssurface facing the image among the lenses in the lens group closest tothe image. The concave lens surface as seen from the image side amongthe optical surfaces in the lens group closest to the image is likely tocause light reflection. To address this, the antireflection film isprovided to the lens surface so that ghosting and flare can beeffectively reduced.

In the zoom optical system ZL according to the present embodiment, theoptical surface provided with the antireflection film is preferably aconcave lens surface as seen from the object. The concave lens surfaceas seen from the object among the optical surfaces in the lens groupclosest to the image with respect to the first lens group G1 is likelyto cause light reflection. To address this, the antireflection film isprovided to the lens surface so that ghosting and flare can beeffectively reduced.

In the zoom optical system ZL according to the present embodiment, theconcave lens surface as seen from the object is preferably a lenssurface facing the image among the lenses in the first lens group G1.The concave lens surface as seen from the object among the opticalsurfaces in the first lens group G1 is likely to cause light reflection.To address this, the antireflection film is provided to the lens surfaceso that ghosting and flare can be effectively reduced.

In the zoom optical system ZL according to the present embodiment, theantireflection film is preferably a multi-layered film, and theoutermost layer of the multi-layered film is the layer with a refractiveindex nd of 1.3 or less. With this configuration, the difference inrefractive index between the layer with a refractive index nd of 1.30 orless and the air can be reduced, resulting in less reflection of lightto reduce ghosting and flare.

The antireflection film in the zoom optical system ZL according to thepresent embodiment may be formed by a wet process, a dry process, or thelike. In the case of the dry process, the antireflection film preferablyincludes at least one layer with a refractive index nd of 1.30 or less.With this configuration, even when the antireflection film is formed bythe dry process or the like, the same effects can be achieved as withthe antireflection film formed by the wet process. The layer with arefractive index nd of 1.30 or less is preferably the outermost layer ofthe multi-layered film.

While the conditions and configurations described above are designed toexert the above-described effects, the embodiment does not necessarilysatisfy all the conditions and configurations. The above-describedeffects can be achieved by any of the conditions and configurations orby a combination of any of the conditions and configurations.

Next, a camera that is an optical device including the zoom opticalsystem ZL according to the present embodiment is described withreference to FIG. 16. This camera 1 is what is known as a mirrorlesscamera that is a lens interchangeable camera and includes the zoomoptical system ZL according to the present embodiment serving as animaging lens 2. In the camera 1, the imaging lens 2 collects light froman object (subject) (not illustrated) and a subject image is formed onan imaging surface of an imaging unit 3 through an optical low passfilter (OLPF) (not illustrated). A photoelectric conversion elementincluded in the imaging unit 3 performs photoelectric conversion of thesubject image to form an image of the subject. This image is displayedon an electronic view finder (EVF) 4 included in the camera 1. In thismanner, the photographer can observe the subject through the EVF 4.

When the photographer presses a release button (not illustrated), theimage photoelectrically converted by the imaging unit 3 is stored in amemory (not illustrated). In this manner, the photographer can capturean image of the subject with the camera 1. While a mirrorless camera istaken as an example in the present embodiment, the same effects as withthe camera 1 can be achieved when the zoom optical system ZL accordingto the present embodiment is installed in a single lens reflex camerathat includes a quick return mirror in a camera body and captures animage of a subject through a finder optical system.

The following configurations can be appropriately employed withoutcompromising the optical performance.

The configurations of the zoom optical system ZL with the five and sixgroups are described in the present embodiment. However, this should notbe construed in a limiting sense, and the present invention can beapplied to a configuration with other number of groups, such as seven oreight groups or the like. A configuration further provided with a lensor a lens group closest to an object or further provided with a lens ora lens group closest to the image may be employed. More specifically, alens group the position of which facing the image surface is fixed uponzooming or focusing may be added to the side closest to the imagesurface. The lens group is a portion including at least one lensseparated from another lens with a distance varying upon zooming orfocusing. In the zoom optical system ZL according to the embodiment, thefirst lens group G1 to the fifth lens group G5 move along the opticalaxis to change the distances between the groups upon zooming. A lenscomponent refers to a cemented lens in which a single lens or aplurality of lenses are cemented.

By moving a single or a plurality of lens groups or a partial lens groupin the optical axis direction, a focusing lens group may be providedthat performs focusing from an infinite distant object to a shortdistance object. In this case, the focus lens group can be applied toauto focus, and is suitable for motor driving for auto focus (forsupersonic wave motors, etc.). In particular, at least a part of thesecond lens group G2 is preferably a focusing lens group, and thepositions of the other lenses are fixed with respect to the imagesurface upon focusing. The focusing lens group preferably includes asingle lens in terms of load on the motor.

The lens groups may be entirely or partially moved with a displacementcomponent in a direction orthogonal to the optical axis, or may be movedand rotated (swing) within an in-plane direction including the opticalaxis, to serve as a vibration-proof lens group for correcting image blurdue to camera shake or the like. As described above, at least a part ofthe fourth lens group G4 is especially preferably used as thevibration-proof lens group.

The lens surface may be formed to have a spherical surface or a planersurface, or may be formed to have an aspherical shape. The lens surfacehaving a spherical surface or a planer surface features easy lensprocessing and assembly adjustment, which leads to the processing andassembly adjustment less likely to involve an error compromising theoptical performance, and thus is preferable. Furthermore, there is anadvantage in that rendering performance is not largely compromised evenwhen the image surface is displaced. The lens surface having anaspherical shape may be achieved with any one of an aspherical shapeformed by grinding, a glass-molded aspherical shape obtained by moldinga glass piece into an aspherical shape, and a composite type asphericalsurface obtained by providing an aspherical shape resin piece on a glasssurface. A lens surface may be a diffractive surface. The lens may be agradient index lens (GRIN lens) or a plastic lens.

The aperture stop S is preferably disposed in the neighborhood of orwithin the third lens group G3. Alternatively, a lens frame may serve asthe aperture stop so that the member serving as the aperture stop needsnot to be provided.

The lens surfaces may be provided with an antireflection film featuringhigh transmittance over a wide range of wavelengths to achieve anexcellent optical performance with reduced flare and ghosting andincreased contrast.

The zoom optical system ZL according to the present embodiment haszooming rates of about 3 to 10 times.

Next, a method for manufacturing the zoom optical system ZL according tothe present embodiment is schematically described with reference to FIG.17. First, the lenses are arranged to prepare the first lens group G1,the second lens group G2, the third lens group G3, the fourth lens groupG4, and the fifth lens group G5, and upon zooming from the wide angleend state to the telephoto end state, the lens groups G1 to G5 are movedalong the optical axis to change a distance between the lens groups G1to G5 (step S100). In the fifth lens group G5, at least one positivelens and at least one negative lens are arranged (step S200). The lensesare arranged in such a manner that the above-described conditions (forexample, conditional expressions (1) and (2)) are satisfied (step S300).

More specifically, in the present embodiment, as illustrated in FIG. 1,for example, in order from the object, the first lens group G1 includes:a cemented lens including a negative meniscus lens L11 having a convexsurface facing the object and a biconvex lens L12, and a positivemeniscus lens L13 having a convex surface facing the object; the secondlens group G2 includes: a negative meniscus lens L21 having a convexsurface facing the object provided with a resin layer to form anaspherical surface, a biconcave lens L22, a biconvex lens L23, and anegative meniscus lens L24 having a concave surface facing the object;the third lens group G3 includes: an aperture stop S, a biconvex lensL31, a cemented lens including a biconvex lens L32 and a negativemeniscus lens L33 having a concave surface facing the object, and abiconvex lens L34; the fourth lens group G4 includes a cemented lensincluding a biconcave negative lens L41 having an aspherical surface onthe lens surface facing the object and a positive meniscus lens L42having a convex surface facing the object, and a negative meniscus lensL43 having a concave surface facing the object; and the fifth lens groupG5 includes a plano-convex lens L51 having a planar surface facing theobject, and a cemented lens including a biconvex lens L52 and a negativelens L53 having a negative meniscus lens shape having an asphericalshape on the lens surface facing the image. The zoom optical system ZLis manufactured by arranging the lens groups thus prepared in the mannerdescribed above.

With the configuration described above, the zoom optical system ZL thatis compact and has high optical performance, and an optical deviceincluding the zoom optical system ZL and a method for manufacturing thezoom optical system ZL can be provided.

EXAMPLES

Examples according to the present application are described withreference to the drawings. FIG. 1, FIG. 6, and FIG. 11 arecross-sectional views illustrating configurations and refractive powerdistributions of the zoom optical system ZL (ZL1 to ZL3) according toExamples. In the lower portion of each cross-sectional view of the zoomoptical systems ZL1 to ZL3, the directions in which the lens groups G1to G5 (or G6) are moved along the optical axis upon zooming from thewide angle end state (W) via the intermediate focal length state (M) tothe telephoto end state (T) are shown by arrows.

In each Example, the aspherical surface is represented by the followingequation (a) where y denotes a height in the direction orthogonal to theoptical axis, S (y) denotes a distance (sag amount) along the opticalaxis from a tangential plane of a vertex of the aspherical surface atthe height y to the aspherical surface, r denotes a radius of curvature(paraxial radius of curvature) of a reference spherical surface, aconical coefficient K, and A_(n) denotes an n-th aspherical coefficient.In the following Examples, “E-n” indicates “×10^(−n)”.S(y)=(y ² /r)/{1+(1−K×y ² /r ²)^(1/2) }+A4×y ⁴ +A6×y ⁶ +A8×y ⁸ +A10×y ¹⁰+A12×y ²  (a)

In each Example, a secondary aspherical coefficient A2 is 0. In Tablesof Examples, the aspherical surface is denoted by * on the right side ofthe surface number.

Example 1

FIG. 1 is a diagram illustrating the configuration of the zoom opticalsystem ZL1 according to Example 1. The zoom optical system ZL1illustrated in FIG. 1 has a configuration including: a first lens groupG1 having positive refractive power; a second lens group G2 havingnegative refractive power; a third lens group G3 having positiverefractive power; a fourth lens group 4G having negative refractivepower; and a fifth lens group G5 having positive refractive power thatare disposed in order from an object.

In the zoom optical system ZL1, the first lens group G1 includes: acemented lens including a negative meniscus lens L11 having a convexsurface facing the object and a biconvex lens L12; and a positivemeniscus lens L13 having a convex surface facing the object that aredisposed in order from an object. The second lens group G2 includes: anegative meniscus lens L21 having a convex surface facing the objectprovided with a resin layer on the lens surface facing the object toform an aspherical surface; a biconcave lens L22; a biconvex lens L23;and a negative meniscus lens L24 having a concave surface facing theobject that are disposed in order from the object. The third lens groupG3 includes: a biconvex lens L31; a cemented lens including a biconvexlens L32 and a negative meniscus lens L33 having a concave surfacefacing the object; and a biconvex lens L34 that are disposed in orderfrom the object. The fourth lens group G4 includes: a fourth-A lensgroup G4A having negative refractive power and including a cemented lensincluding a negative biconcave lens L41 having an aspherical lenssurface facing the object and a positive meniscus lens L42 having aconvex surface facing the object; and a fourth-B lens group G4B havingnegative refractive power and including a negative meniscus lens L43having a concave surface facing the object that are disposed in orderfrom the object. The fifth lens group G5 includes: a plano-convex lensL51 having a planar surface facing the object, and a cemented lensincluding a biconvex lens L52 and a negative meniscus lens L53 having anaspherical lens surface facing the image that are disposed in order fromthe object. An aperture stop S is provided adjacent to and more on theobject side than the third lens group G3. The negative lens L41 and thenegative lens L53 are glass-molded aspherical lenses.

In the zoom optical system ZL1, upon zooming from a wide angle end stateto a telephoto end state, the lens groups are configured to be movedtoward the object along the optical axis to increase a distance betweenthe first lens group G1 and the second lens group G2, decrease adistance between the second lens group G2 and the third lens group G3,increase a distance between the third lens group G3 and the fourth lensgroup G4, and decrease a distance between the fourth lens group G4 andthe fifth lens group G5. The aperture stop S integrally moves with thethird lens group G3. The third lens group G3 and the fifth lens group G5are configured to move with the same movement amount with respect to theimage surface.

The zoom optical system ZL1 is configured to perform focusing frominfinity to a short-distant object by moving the second lens group G2toward the object.

The zoom optical system ZL1 is configured to perform correction(vibration isolation) on the position of the image when image shake hasoccurred by moving the fourth-A lens group G4A in the fourth lens groupG4 to have a displacement component in the direction orthogonal to theoptical axis. To correct roll blur of an angle θ with a lens having afocal length f of the whole system and a vibration proof coefficient K(the ratio of the image movement amount on the imaging surface to themovement amount of the fourth-A lens group G4A in correction of theimage position when image shake has occurred), the fourth-A lens groupG4A, which is a vibration-proof lens group, is moved in the directionorthogonal to the optical axis by (f·tan θ)/K (the same applies toExamples below). In the wide angle end state in Example 1, the vibrationproof coefficient is −0.65 and the focal length is 16.49 (mm), and thusthe movement amount of the fourth-A lens group G4A to correct a rollblur of 0.50° is −0.22 (mm). In the intermediate focal length state inExample 1, the vibration proof coefficient is −0.79 and the focal lengthis 35.00 (mm), and thus the movement amount of the fourth-A lens groupG4A to correct a roll blur of 0.50° is −0.39 (mm). In the telephoto endstate in Example 1, the vibration proof coefficient is −0.99 and thefocal length is 77.79 (mm), and thus the movement amount of the fourth-Alens group G4A to correct a roll blur of 0.50° is −0.68 (mm).

Table 1 below lists specification values of the zoom optical system ZL1.In Table 1, among the specifications, f denotes the focal length of thewhole system, FNO denotes an F number, ω denotes a half angle of view, Ydenotes a maximum image height, TL denotes a total length, and BFdenotes a value of back focus in each of the wide angle end state, theintermediate focal length state, and the telephoto end state. The totallength TL represents the distance from the lens surface (first surfacein FIG. 1) closest to the object upon focusing on infinity to the imagesurface I on the optical axis. The back focus BF represents the distance(air equivalent length) from the lens surface (32nd surface in FIG. 1)closest to the image surface upon focusing on infinity to the imagesurface I on the optical axis. In the lens data, the first column mrepresents the order (surface number) of lens surfaces from the objectside along the direction in a traveling direction of a light beam, thesecond column r represents a radius of curvature of each lens surface,the third column d represents a distance (surface distance) between eachoptical surface and the next optical surface on the optical axis, andthe fourth column nd and the fifth column vd represent a refractiveindex and an Abbe number of the material based on the d line (λ=587.6nm). A radius of curvature 0.000 indicates a flat surface, and arefractive index of air 1.00000 is not mentioned. Surface numbers 1 to32 listed in Table 1 correspond to numbers m1 to m32 in FIG. 1 (FIG. 1shows a part of the surface numbers). The focal lengths of the lensgroups indicate focal lengths from the respective starting surfaces ofthe first lens group G1 to the fifth lens group G5.

The focal length f, the radius of curvature r, the surface distance d,and the other units of length described below as the specificationvalues, which are generally described with “mm” unless otherwise notedshould not be construed in a limiting sense because the optical systemproportionally expanded or reduced can have similar or the same opticalperformance. The description on the numerals and the specification listssimilarly applies to the other Examples.

TABLE 1 Example 1 [Overall specifications] Wide angle Intermediate focalTelephoto end state length state end state f = 16.49 ~ 35.00 ~ 77.79 FNo= 2.72 ~ 3.38 ~ 4.16 ω = 43.2 ~ 22.0 ~ 10.4 Y = 14.75 ~ 14.75 ~ 14.75 TL= 130.371 ~ 146.181 ~ 171.571 BF = 37.994 ~ 49.378 ~ 63.528 BF(air =37.994 ~ 49.378 ~ 63.528 equivalent length) [Lens data] m r d nd νdObject ∞ surface  1 142.08408 1.800 1.84666 23.8  2 61.98900 6.8001.59319 67.9  3 2234.55748 0.100  4 54.61907 4.400 1.81600 46.6  5160.87634 D5  6* 111.35036 0.200 1.56093 36.6  7 74.66256 1.200 1.8160046.6  8 13.29818 6.450  9 −26.94042 1.000 1.81600 46.6 10 41.14663 0.80011 38.15106 4.500 1.84666 23.8 12 −28.49989 0.500 13 −21.99346 1.0001.88300 40.7 14 −53.69291 D14 15 0.00000 1.600 Aperture stop S 16237.40240 3.500 1.54814 45.8 17 −29.52544 0.150 18 41.68613 4.2001.51742 52.2 19 −26.94900 1.100 1.90200 25.3 20 −425.16586 0.100 2137.61777 2.850 1.49782 82.6 22 −64.06628 D22 23* −69.82119 0.800 1.7905045.0 24 24.82010 2.000 1.90200 25.3 25 100.53108 2.550 26 −22.078311.000 1.81600 46.6 27 −33.57787 D27 28 0.00000 4.600 1.49782 82.6 29−20.99670 0.100 30 71.45078 6.100 1.49782 82.6 31 −20.04840 1.2001.88202 37.2 32* −55.06437 BF Image ∞ surface [Focal lengths of lensgroups] Starting Focal Lens group surface length First lens group 186.49 Second lens group 6 −13.10 Third lens group 15 24.85 Fourth lensgroup 23 −35.11 Fifth lens group 28 36.01

In the zoom optical system ZL1, 6th, 23rd, and 32nd surfaces haveaspherical shapes. Table 2 lists aspherical data, that is, a conicalcoefficient K and aspherical coefficients A4 to A12.

TABLE 2 [Aspherical data] A4 A6 A8 A10 A12 6th surface K = 1.00000e+001.91866e−05 −3.07743e−08 −1.44905e−10 1.15106e−12 −1.98690e−15  23rdsurface K = 1.00000e+00 3.75789e−06 −1.80254e−08  0.00000e+000.00000e+00 0.00000e+00 32nd surface K = 1.00000e+00 7.46360e−06 8.05331e−09 −4.65179e−11 2.16314e−13 0.00000e+00

In the zoom optical system ZL1, the axial distance D5 between the firstlens group G1 and the second lens group G2, the axial distance D14between the second lens group G2 and the third lens group G3 (aperturestop S), the axial distance D22 between the third lens group G3 and thefourth lens group G4, the axial distance D27 between the fourth lensgroup G4 and the fifth lens group G5, and the back focus BF are changedupon zooming as described above. Table 3 below lists variable distancesin each focal length state of the wide angle end state (W), theintermediate focal length state (M), and the telephoto end state (T) inthe focusing-on-infinity state and thefocusing-on-a-short-distant-object state. DO denotes the distance fromthe surface (first surface) closest to the object in the zoom opticalsystem ZL1 to the object, and β denotes a magnification (the sameapplies to Examples below).

TABLE 3 [Variable distance data] Infinity Short distance W M T W M T D0∞ ∞ ∞ 219.63 203.82 178.43 β — — — −0.0648 −0.1260 −0.2249 f 16.49 35.0077.79 — — — D5 2.100 17.730 35.502 0.885 15.776 31.579 D14 18.846 7.6421.110 20.061 9.596 5.033 D22 1.434 6.306 9.411 1.434 6.306 9.411 D279.397 4.525 1.420 9.397 4.525 1.420 BF 37.994 49.378 63.528 37.99449.378 63.528

Next, Table 4 lists conditional expression corresponding values in thezoom optical system ZL1. In Table 4, fw denotes the focal length of thewhole system in the wide angle end state, ft denotes the focal length ofthe whole system in the telephoto end state, f1 denotes the focal lengthof the first lens group G1, f2 denotes the focal length of the secondlens group G2, f3 denotes the focal length of the third lens group G3,f4 denotes the focal length of the fourth lens group G4, f5w denotes thecomposite focal length of the optical system on the image side includingthe fifth lens group G5 in the wide angle end state, ωw denotes a halfangle of view in the wide angle end state, ωt denotes a half angle ofview in the telephoto end state, FNw denotes the F number of the wholesystem in the wide angle end state, FNt denotes the F number of thewhole system in the telephoto end state, N2max denotes a maximumabsolute value of the refractive index with respect to the d line of thelens medium in the second lens group G2, N3n denotes an averagerefractive index with respect to the d line of all the negative lensmedia in the third lens group G3, N3p denotes an average refractiveindex with respect to the d line of all the positive lens media in thethird lens group G3, N5n denotes an average refractive index withrespect to the d line of all the negative lens media in the fifth lensgroup G5, and N5p denotes an average refractive index with respect tothe d line of all the positive lens media in the fifth lens group G5.The description on the numerals similarly applies to the other Examplesdescribed below.

TABLE 4 f5w = 36.01 [Conditional expression corresponding values] (1)(−f4)/f5w = 0.975  (2)FNw = 2.722  (3)N5n − N5p = 0.384  (4)N5n =1.882  (5)ft/fw = 4.717  (6)FNt = 4.160  (7)f1/f3 = 3.480  (8)f2/f4 =0.371  (9)N2max = 1.883 (10)fw/f3 = 0.664 (11)fw/(−f4) = 0.470 (12)ft/f3= 3.130 (13)ft/(−f4) = 2.216 (14)N3n − N3p = 0.381 (15)N3n = 1.902(16)ωw = 43.244 (17)ωt = 10.411

In this manner, the zoom optical system ZL1 satisfies all theconditional expressions (1) to (17) described above.

FIG. 2A, FIG. 3A, and FIG. 4A illustrate spherical aberrations,astigmatism aberrations, distortion aberrations, lateral chromaticaberrations, and lateral aberrations of the zoom optical system ZL1 inthe wide angle end state, the intermediate focal length state, and thetelephoto end state upon focusing on infinity. FIG. 2B, FIG. 3B, andFIG. 4B illustrate lateral aberrations of the zoom optical system ZL1performing image blur correction in the wide angle end state, theintermediate focal length state, and the telephoto end state uponfocusing on infinity. FIGS. 5A-5C illustrate spherical aberrations,astigmatism aberrations, distortion aberrations, lateral chromaticaberrations, and lateral aberrations of the zoom optical system ZL1 inthe wide angle end state, the intermediate focal length state, and thetelephoto end state upon focusing on a short distance object. In theaberration graphs, FNO denotes an F number, A denotes a half angle ofview (unit [°]), NA denotes the number of apertures, and H0 denotes anobject height. The spherical aberration graphs illustrate an F number orthe number of apertures corresponding to the maximum aperture,astigmatism aberration graphs and distortion aberration graphsillustrate a half angle of view or the maximum object height, andlateral aberration graphs illustrate half angles of view or objectheights. d denotes a d line (λ=587.6 nm) and g denotes a g line (λ=435.8nm). In the astigmatism aberration graphs, a solid line represents asagittal image surface, and a broken line represents a meridional imagesurface. In aberration graphs in Examples described below, the samereference signs as in this Example are used. It can be seen in theseaberration graphs that the zoom optical system ZL1 can achieve anexcellent imaging performance with various aberrations successfullycorrected from the wide angle end state to the telephoto end state.

Example 2

FIG. 6 is a diagram illustrating the configuration of the zoom opticalsystem ZL2 according to Example 2. The zoom optical system ZL2illustrated in FIG. 6 has a configuration including: a first lens groupG1 having positive refractive power; a second lens group G2 havingnegative refractive power; a third lens group G3 having positiverefractive power; a fourth lens group 4G having negative refractivepower; and a fifth lens group G5 having positive refractive power thatare disposed in order from an object.

In the zoom optical system ZL2, the first lens group G1 includes: acemented lens including a negative meniscus lens L11 having a convexsurface facing the object and a biconvex lens L12; and a positivemeniscus lens L13 having a convex surface facing the object that aredisposed in order from an object. The second lens group G2 includes: anegative meniscus lens L21 having a convex surface facing the objectprovided with a resin layer on the lens surface facing the object toform an aspherical surface; a biconcave lens L22; a biconvex lens L23;and a negative meniscus lens L24 having a concave surface facing theobject that are disposed in order from the object. The third lens groupG3 includes: a biconvex lens L31; a cemented lens including a biconvexlens L32 and a negative meniscus lens L33 having a concave surfacefacing the object; and a biconvex lens L34 that are disposed in orderfrom the object. The fourth lens group G4 includes: a fourth-A lensgroup G4A having negative refractive power and including a cemented lensincluding a negative biconcave lens L41 having an aspherical lenssurface facing the object and a positive meniscus lens L42 having aconvex surface facing the object; and a fourth-B lens group G4B havingnegative refractive power and including a negative meniscus lens L43having a concave surface facing the object that are disposed in orderfrom the object. The fifth lens group G5 includes: abiconvex lens L51; anegative meniscus lens L52 having a convex surface facing the object;and a positive biconvex lens L53 having an aspherical lens surfacefacing the image that are disposed in order from the object. An aperturestop S is provided adjacent to and more on the object side than thethird lens group G3. The negative lens L41 and the positive lens L53 areglass-molded aspherical lenses.

In the zoom optical system ZL2, upon zooming from a wide angle end stateto a telephoto end state, the lens groups are configured to be movedtoward the object along the optical axis to increase a distance betweenthe first lens group G1 and the second lens group G2, decrease adistance between the second lens group G2 and the third lens group G3,increase a distance between the third lens group G3 and the fourth lensgroup G4, and decrease a distance between the fourth lens group G4 andthe fifth lens group G5. The aperture stop S integrally moves with thethird lens group G3. The third lens group G3 and the fifth lens group G5are configured to move with the same movement amount with respect to theimage surface.

The zoom optical system ZL2 is configured to perform focusing frominfinity to a short-distant object by moving the second lens group G2toward the object.

The zoom optical system ZL2 is configured to perform correction(vibration isolation) on the position of the image when image shake hasoccurred by moving the fourth-A lens group G4A in the fourth lens groupG4 to have a displacement component in the direction orthogonal to theoptical axis. In the wide angle end state in Example 2, the vibrationproof coefficient is −0.68 and the focal length is 17.92 (mm), and thusthe movement amount of the fourth-A lens group G4A to correct a rollblur of 0.50° is −0.23 (nm). In the intermediate focal length state inExample 2, the vibration proof coefficient is −0.78 and the focal lengthis 32.00 (nm), and thus the movement amount of the fourth-A lens groupG4A to correct a roll blur of 0.50° is −0.36 (mm). In the telephoto endstate in Example 2, the vibration proof coefficient is −1.01 and thefocal length is 83.00 (mm), and thus the movement amount of the fourth-Alens group G4A to correct a roll blur of 0.50° is −0.72 (mm).

Table 5 below lists specification values of the zoom optical system ZL2.Surface numbers 1 to 33 listed in Table 5 correspond to numbers m1 tom33 in FIG. 6 (FIG. 6 shows a part of the surface numbers).

TABLE 5 Example 2 [Overall specifications] Wide angle Intermediate focalTelephoto end state length state end state f = 17.92 ~ 32.00 ~ 83.00 FNo= 2.44 ~ 2.92 ~ 3.77 ω = 40.0 ~ 23.4 ~ 9.5 Y = 14.25 ~ 14.25 ~ 14.25 TL= 132.419 ~ 144.654 ~ 174.652 BF = 41.537 ~ 49.713 ~ 65.542 BF (air =41.537 ~ 49.713 ~ 65.542 equivalent length) [Lens data] m r d nd νdObject ∞ surface  1 167.51126 1.800 1.84666 23.8  2 65.36598 6.8001.59319 67.9  3 −2500.00000 0.100  4 53.28844 4.400 1.81600 46.6  5148.73119 D5  6* 98.04448 0.200 1.56093 36.6  7 60.00000 1.200 1.8040046.6  8 14.40723 6.471  9 −27.00000 1.000 1.81600 46.6 10 49.41381 0.74911 42.76510 4.500 1.84666 23.8 12 −29.37797 1.000 13 −19.04811 1.0001.88300 40.7 14 −46.90749 D14 15 0.00000 0.400 Aperture stop S 16436.00582 2.927 1.54814 45.8 17 −30.11148 0.150 18 59.43487 4.0001.48749 70.3 19 −28.97361 1.100 1.90200 25.3 20 −62.61619 0.100 2156.98362 2.750 1.49782 82.6 22 −76.57983 D22 23* −41.28693 0.800 1.7905045.0 24 37.52861 2.000 1.90200 25.3 25 −3339.51980 3.000 26 −26.162461.000 1.72916 54.6 27 −49.02058 D27 28 36.11715 4.600 1.49782 82.6 29−43.89441 0.100 30 67.43312 1.200 1.91748 28.6 31 25.37662 1.310 3237.12949 4.271 1.49786 82.5 33* −39.01900 BF Image ∞ surface [Focallengths of lens groups] Starting Focal Lens group surface length Firstlens group 1 87.89 Second lens group 6 −13.10 Third lens group 15 24.40Fourth lens group 23 −33.98 Fifth lens group 28 36.22

In the zoom optical system ZL2, 6th, 23rd, and 33rd surfaces haveaspherical shapes. Table 6 lists aspherical data, that is, a conicalcoefficient K and aspherical coefficients A4 to A12.

TABLE 6 [Aspherical data] A4 A6 A8 A10 A12 6th surface K = 1.00000e+001.85470e−05 −4.02525e−08  2.54277e−10 −1.05685e−12  3.80620e−15 23rdsurface K = 1.00000e+00 3.85870e−06 6.25371e−10 0.00000e+00 0.00000e+000.00000e+00 33rd surface K = −3.93240e+00 2.65953e−06 1.69344e−08−8.71281e−13  1.49597e−13 0.00000e+00

In the zoom optical system ZL2, the axial distance D5 between the firstlens group G1 and the second lens group G2, the axial distance D14between the second lens group G2 and the third lens group G3 (aperturestop S), the axial distance D22 between the third lens group G3 and thefourth lens group G4, the axial distance D27 between the fourth lensgroup G4 and the fifth lens group G5, and the back focus BF are changedupon zooming as described above. Table 7 below lists variable distancesin each focal length state of the wide angle end state (W), theintermediate focal length state (M), and the telephoto end state (T) inthe focusing-on-infinity state and thefocusing-on-a-short-distant-object state.

TABLE 7 [Variable distance data] Infinity Short distance W M T W M T D0∞ ∞ ∞ 217.58 205.35 175.35 β — — — −0.0704 −0.1176 −0.2335 f 17.92 32.0083.00 — — — D5 2.650 15.012 36.908 1.386 13.195 32.734 D14 18.429 10.1262.400 19.693 11.944 6.574 D22 1.400 5.657 9.876 1.400 5.657 9.876 D279.476 5.219 1.000 9.476 5.219 1.000 BF 41.537 49.713 65.542 41.53749.713 65.542

Next, Table 8 lists conditional expression corresponding values in thezoom optical system ZL2.

TABLE 8 f5w = 36.22 [Conditional expression corresponding values] (1)(−f4)/f5w = 0.938  (2)FNw = 2.443  (3)N5n − N5p = 0.420  (4)N5n =1.917  (5)ft/fw = 4.632  (6)FNt = 3.769  (7)f1/f3 = 3.602  (8)f2/f4 =0.385  (9)N2max = 1.883 (10)fw/f3 = 0.734 (11)fw/(−f4) = 0.527 (12)ft/f3= 3.401 (13)ft/(−f4) = 2.442 (14)N3n − N3p = 0.391 (15)N3n = 1.902(16)ωw = 39.990 (17)ωt = 9.463

In this manner, the zoom optical system ZL2 satisfies all theconditional expressions (1) to (17) described above.

FIG. 7A, FIG. 8A, and FIG. 9A illustrate spherical aberrations,astigmatism aberrations, distortion aberrations, lateral chromaticaberrations, and lateral aberrations of the zoom optical system ZL2 inthe wide angle end state, the intermediate focal length state, and thetelephoto end state upon focusing on infinity. FIG. 7B, FIG. 8B, andFIG. 9B illustrate lateral aberrations of the zoom optical system ZL2performing image blur correction in the wide angle end state, theintermediate focal length state, and the telephoto end state uponfocusing on infinity. FIGS. 10A-10C illustrate spherical aberrations,astigmatism aberrations, distortion aberrations, lateral chromaticaberrations, and lateral aberrations of the zoom optical system ZL2 inthe wide angle end state, the intermediate focal length state, and thetelephoto end state upon focusing on a short distance object. It can beseen in these aberration graphs that the zoom optical system ZL2 canachieve an excellent imaging performance with various aberrationssuccessfully corrected from the wide angle end state to the telephotoend state.

Example 3

FIG. 11 is a diagram illustrating the configuration of the zoom opticalsystem ZL3 according to Example 3. The zoom optical system ZL3illustrated in FIG. 11 has a configuration including: a first lens groupG1 having positive refractive power; a second lens group G2 havingnegative refractive power; a third lens group G3 having positiverefractive power; a fourth lens group 4G having negative refractivepower; a fifth lens group G5 having positive refractive power; and asixth lens group G6 having positive refractive power that are disposedin order from an object.

In the zoom optical system ZL3, the first lens group G1 includes: acemented lens including a negative meniscus lens L11 having a convexsurface facing the object and a biconvex lens L12; and a positivemeniscus lens L13 having a convex surface facing the object that aredisposed in order from an object. The second lens group G2 includes: anegative meniscus lens L21 having a convex surface facing the objectprovided with a resin layer on the lens surface facing the object toform an aspherical surface; a biconcave lens L22; a biconvex lens L23;and a negative meniscus lens L24 having a concave surface facing theobject that are disposed in order from the object. The third lens groupG3 includes: a biconvex lens L31; a cemented lens including a biconvexlens L32 and a negative meniscus lens L33 having a concave surfacefacing the object; and a biconvex lens L34 that are disposed in orderfrom the object. The fourth lens group G4 includes: a fourth-A lensgroup G4A having negative refractive power and including a cemented lensincluding a negative biconcave lens L41 having an aspherical lenssurface facing the object and a positive meniscus lens L42 having aconvex surface facing the object; and a fourth-B lens group G4B havingnegative refractive power and including a negative meniscus lens L43having a concave surface facing the object that are disposed in orderfrom the object. The fifth lens group G5 includes: a biconvex lens L51,and a cemented lens including a positive biconvex lens L52 having anaspherical lens surface facing the object and a negative meniscus lensL53 having a concave surface facing the object that are disposed inorder from the object. The sixth lens group G6 includes: a positivemeniscus lens L61 having a concave surface facing the object and havingan aspherical lens surface facing the image. An aperture stop S isprovided adjacent to and more on the object side than the third lensgroup G3. The negative lens L41, the positive lens L52, and the positivelens L61 are glass-molded aspherical lenses.

In the zoom optical system ZL3, upon zooming from a wide angle end stateto a telephoto end state, the lens groups are configured to be movedtoward the object along the optical axis to increase a distance betweenthe first lens group G1 and the second lens group G2, decrease adistance between the second lens group G2 and the third lens group G3,increase a distance between the third lens group G3 and the fourth lensgroup G4, decrease a distance between the fourth lens group G4 and thefifth lens group G5, and increase a distance between the fifth lensgroup G5 and the sixth lens group G6. The aperture stop S integrallymoves with the third lens group G3. The third lens group G3 and thefifth lens group G5 are configured to move with the same movement amountwith respect to the image surface.

The zoom optical system ZL3 is configured to perform focusing frominfinity to a short-distant object by moving the second lens group G2toward the object.

The zoom optical system ZL3 is configured to perform correction(vibration isolation) on the position of the image when image shake hasoccurred by moving the fourth-A lens group G4A in the fourth lens groupG4 to have a displacement component in the direction orthogonal to theoptical axis. In the wide angle end state in Example 3, the vibrationproof coefficient is −0.67 and the focal length is 18.60 (mm), and thusthe movement amount of the fourth-A lens group G4A to correct a rollblur of 0.50° is −0.24 (mm). In the intermediate focal length state inExample 3, the vibration proof coefficient is −0.76 and the focal lengthis 31.80 (mm), and thus the movement amount of the fourth-A lens groupG4A to correct a roll blur of 0.50° is −0.37 (mm). In the telephoto endstate in Example 3, the vibration proof coefficient is −0.95 and thefocal length is 77.81 (mm), and thus the movement amount of the fourth-Alens group G4A to correct a roll blur of 0.50° is −0.71 (mm).

Table 9 below lists specification values of the zoom optical system ZL3.Surface numbers 1 to 34 listed in Table 9 correspond to numbers m1 tom34 in FIG. 11 (FIG. 11 shows a part of the surface numbers).

TABLE 9 Example 3 [Overall specifications] Wide angle Intermediate focalTelephoto end state length state end state f = 18.60 ~ 31.80 ~ 77.81 FNo= 2.01 ~ 2.34 ~ 2.96 ω = 38.9 ~ 23.5 ~ 10.1 Y = 14.25 ~ 14.25 ~ 14.25 TL= 134.524 ~ 147.355 ~ 176.966 BF = 38.015 ~ 45.607 ~ 60.406 BF (air =38.015 ~ 45.607 ~ 60.406 equivalent length) [Lens data] m r d nd νdObject ∞ surface  1 160.52802 1.800 1.84666 23.8  2 65.03652 6.8001.59319 67.9  3 −2500.00000 0.100  4 52.64606 4.400 1.81600 46.6  5143.14329 D5  6* 96.56216 0.200 1.56093 36.6  7 60.00000 1.200 1.8040046.6  8 14.83792 6.143  9 −27.00000 1.000 1.81600 46.6 10 44.96605 0.85311 43.56313 4.500 1.84666 23.8 12 −24.56322 0.812 13 −18.65534 1.0001.88300 40.7 14 −61.97483 D14 15 0.00000 0.400 Aperture stop S 16159.25973 3.913 1.58913 61.2 17 −34.07018 0.150 18 47.41744 5.3101.57479 62.2 19 −36.74413 1.100 1.90200 25.3 20 −177.06283 0.100 2162.88551 3.778 1.49782 82.6 22 −66.42221 D22 23* −41.70870 0.800 1.7905045.0 24 42.89444 2.100 1.90200 25.3 25 −2019.67150 3.000 26 −26.604281.000 1.72916 54.6 27 −53.45527 D27 28 1984.71100 4.800 1.50514 74.0 29−25.14230 0.100 30* 64.22325 5.500 1.49782 82.6 31 −26.83334 1.2001.88202 37.2 32 −326.49263 D32 33 −64.59872 3.428 1.49782 82.6 34*−25.07133 BF Image ∞ surface [Focal lengths of lens groups] StartingFocal Lens group surface length First lens group 1 86.55 Second lensgroup 6 −13.10 Third lens group 15 23.83 Fourth lens group 23 −33.00Fifth lens group 28 56.67 Sixth lens group 33 80.00

In the zoom optical system ZL3, 6th, 23rd, 30th, and 34th surfaces haveaspherical shapes. Table 10 lists aspherical data, that is, a conicalcoefficient K and aspherical coefficients A4 to A12.

TABLE 10 [Aspherical data] A4 A6 A8 A10 A12 6th surface K = 1.00000e+00 1.75539e−05 −6.44055e−09 −1.64524e−10 1.05588e−12 6.14360e−16 23rdsurface K = 1.00000e+00  5.80858e−06 −1.19924e−08  0.00000e+000.00000e+00 0.00000e+00 30th surface K = −1.79426e+01 −7.47242e−06 1.89731e−08 −3.85325e−10 9.87434e−13 0.00000e+00 34th surface K =4.62100e−01 −7.86061e−07  2.71115e−08 −2.30871e−10 4.72584e−130.00000e+00

In the zoom optical system ZL3, the axial distance D5 between the firstlens group G1 and the second lens group G2, the axial distance D14between the second lens group G2 and the third lens group G3 (aperturestop S), the axial distance D22 between the third lens group G3 and thefourth lens group G4, the axial distance D27 between the fourth lensgroup G4 and the fifth lens group G5, the axial distance D32 between thefifth lens group G5 and the sixth lens group G6, and the back focus BFare changed upon zooming as described above. Table 11 below listsvariable distances in each focal length state of the wide angle endstate (W), the intermediate focal length state (M), and the telephotoend state (T) in the focusing-on-infinity state and thefocusing-on-a-short-distant-object state.

TABLE 11 [Variable distance data] Short Infinity distance W M T W M T D0∞ ∞ ∞ 215.48 202.64 173.03 β — — — −0.0737 −0.1184 −0.2280 f 18.60 31.8077.81 — — — D5 2.336 14.327 34.805 1.052 12.483 30.752 D14 17.818 10.0662.400 19.102 11.910 6.452 D22 1.400 4.791 8.625 1.400 4.791 8.625 D278.224 4.833 1.000 8.224 4.833 1.000 D32 1.244 2.244 4.244 1.244 2.2444.244 BF 38.015 45.607 60.406 38.015 45.607 60.406

Next, Table 12 lists conditional expression corresponding values in thezoom optical system ZL3.

TABLE 12 f5w = 36.20 [Conditional expression corresponding values] (1)(−f4)/f5w = 0.912  (2)FNw = 2.010  (3)N5n − N5p = 0.381  (4)N5n =1.882  (5)ft/fw = 4.183  (6)FNt = 2.957  (7)f1/f3 = 3.631  (8)f2/f4 =0.397  (9)N2max = 1.883 (10)fw/f3 = 0.780 (11)fw/(−f4) = 0.564 (12)ft/f3= 3.265 (13)ft/(−f4) = 2.358 (14)N3n − N3p = 0.348 (15)N3n = 1.902(16)ωw = 38.943 (17)ωt = 10.081

In this manner, the zoom optical system ZL3 satisfies all theconditional expressions (1) to (17) described above.

FIG. 12A, FIG. 13A, and FIG. 14A illustrate spherical aberrations,astigmatism aberrations, distortion aberrations, lateral chromaticaberrations, and lateral aberrations of the zoom optical system ZL3 inthe wide angle end state, the intermediate focal length state, and thetelephoto end state upon focusing on infinity. FIG. 12B, FIG. 13B, andFIG. 14B illustrate lateral aberrations of the zoom optical system ZL3performing image blur correction in the wide angle end state, theintermediate focal length state, and the telephoto end state uponfocusing on infinity. FIGS. 15A-15C illustrate spherical aberrations,astigmatism aberrations, distortion aberrations, lateral chromaticaberrations, and lateral aberrations of the zoom optical system ZL3 inthe wide angle end state, the intermediate focal length state, and thetelephoto end state upon focusing on a short distance object. It can beseen in these aberration graphs that the zoom optical system ZL3 canachieve an excellent imaging performance with various aberrationssuccessfully corrected from the wide angle end state to the telephotoend state.

EXPLANATION OF NUMERALS AND CHARACTERS

-   -   1 camera (optical device)    -   ZL (ZL1 to ZL3) zoom optical system    -   G1 first lens group    -   G2 second lens group    -   G3 third lens group    -   G4 fourth lens group    -   G4A fourth-A lens group    -   G4B fourth-B lens group    -   G5 fifth lens group

The invention claimed is:
 1. A zoom optical system comprising in orderfrom an object: a first lens group having positive refractive power; asecond lens group having negative refractive power; a third lens grouphaving positive refractive power; a fourth lens group having negativerefractive power; and a fifth lens group having positive refractivepower, wherein upon zooming from a wide angle end state to a telephotoend state, the lens groups are moved along an optical axis to change adistance between the first lens group and the second lens group, adistance between the second lens group and the third lens group, adistance between the third lens group and the fourth lens group, and adistance between the fourth lens group and the fifth lens group, thefifth lens group includes at least one positive lens and at least onenegative lens, and the following conditional expressions are satisfied:2.50<f1/f3<4.200.80<(−f4)/f5w<2.50FNw<3.503.50<ft/fw0.30<fw/(−f4)<0.80 where, f1 denotes the focal length of the first lensgroup, f3 denotes the focal length of the third lens group, f4 denotes afocal length of the fourth lens group, f5w denotes a composite focallength of an optical system on an image side including the fifth lensgroup in the wide angle end state, FNw denotes an F number of the wholesystem in the wide angle end state, ft denotes the focal length of thewhole system in the telephoto end state, and fw denotes a focal lengthof the whole system in the wide angle end state.
 2. The zoom opticalsystem according to claim 1, wherein the following conditionalexpressions are satisfied:0.30<N5n−N5p1.85<N5n where, N5n denotes an average refractive index with respect toa d line of all negative lens media in the fifth lens group, and N5pdenotes an average refractive index with respect to the d line of allpositive lens media in the fifth lens group.
 3. The zoom optical systemaccording to claim 1, wherein the following conditional expression issatisfied:FNt<4.50 where, FNt denotes an F number of the whole system in thetelephoto end state.
 4. The zoom optical system according to claim 1,wherein upon zooming from the wide angle end state to the telephoto endstate, the lens groups are moved along the optical axis so as toincrease the distance between the first lens group and the second lensgroup, decrease the distance between the second lens group and the thirdlens group, increase the distance between the third lens group and thefourth lens group, and decrease the distance between the fourth lensgroup and the fifth lens group.
 5. The zoom optical system according toclaim 1, wherein the following conditional expression is satisfied:0.25<f2/f4<0.55 where, f2 denotes a focal length of the second lensgroup, and f4 denotes a focal length of the fourth lens group.
 6. Thezoom optical system according to claim 1, wherein the followingconditional expression is satisfied:1.85<N2max where, N2max denotes a maximum absolute value of therefractive index with respect to a d line of a lens medium in the secondlens group.
 7. The zoom optical system according to claim 1, wherein thefollowing conditional expression is satisfied:0.4<fw/f3<1.00 where, f3 denotes a focal length of the third lens group.8. The zoom optical system according to claim 1, wherein the followingconditional expression is satisfied:2.00<ft/f3<5.00 where, f3 denotes a focal length of the third lensgroup.
 9. The zoom optical system according to claim 1, wherein thefollowing conditional expression is satisfied:1.50<ft/(−f4)<4.50.
 10. The zoom optical system according to claim 1,wherein the following conditional expressions are satisfied:0.30<N3n−N3p1.85<N3n where, N3n denotes an average refractive index with respect toa d line of all negative lens media in the third lens group, and N3pdenotes an average refractive index with respect to the d line of allpositive lens media in the third lens group.
 11. The zoom optical systemaccording to claim 1, wherein the following conditional expression issatisfied:25.0°<ωw<60.0° where, ωw denotes a half angle of view in the wide angleend state.
 12. The zoom optical system according to claim 1, wherein thefollowing conditional expression is satisfied:3.0°<ωt<20.0° where, ωt denotes a half angle of view in the telephotoend state.
 13. The zoom optical system according to claim 1, wherein atleast a portion of one of the first lens group, the second lens group,the third lens group, the fourth lens group, and the fifth lens group ismoved to have a displacement component in a direction orthogonal to theoptical axis.
 14. The zoom optical system according to claim 1, whereinthe fourth lens group includes a fourth-A lens group having negativerefractive power, and a fourth-B lens group having negative refractivepower, wherein one of the fourth-A lens group and the fourth-B lensgroup is moved to have a displacement component in a directionorthogonal to the optical axis.
 15. The zoom optical system according toclaim 1, wherein the third lens group and the fifth lens group movetoward the object upon zooming from the wide angle end state to thetelephoto end state with a same movement amount with respect to an imagesurface.
 16. The zoom optical system according to claim 1, wherein atleast a part of the second lens group is moved along the optical axisupon focusing on a short distance object.
 17. An optical devicecomprising the zoom optical system according to claim
 1. 18. A methodfor manufacturing a zoom optical system including, in order from anobject: a first lens group having positive refractive power; a secondlens group having negative refractive power; a third lens group havingpositive refractive power; a fourth lens group having negativerefractive power; and a fifth lens group having positive refractivepower, the method comprising: arranging the lens groups such that, uponzooming from a wide angle end state to a telephoto end state, the lensgroups move along an optical axis to change a distance between the firstlens group and the second lens group, a distance between the second lensgroup and the third lens group, a distance between the third lens groupand the fourth lens group, and a distance between the fourth lens groupand the fifth lens group; arranging at least one positive lens and atleast one negative lens in the fifth lens group; and at least one of thefollowing Features (A) or (B): Feature (A): satisfying the followingconditional expressions:2.50<f1/f3<4.200.80<(−f4)/f5w<2.50FNw<3.503.50<ft/fw0.30<fw/(−f4)<0.80 where, f1 denotes the focal length of the first lensgroup, f3 denotes the focal length of the third lens group, f4 denotes afocal length of the fourth lens group, f5w denotes a composite focallength of an optical system on an image side including the fifth lensgroup in the wide angle end state, FNw denotes an F number of the wholesystem in the wide angle end state, ft denotes the focal length of thewhole system in the telephoto end state, and fw denotes a focal lengthof the whole system in the wide angle end state; Feature (B): arrangingthe second lens group to move toward an object along the optical axisupon focusing on a short distance object from an infinitely distantobject, arranging at least a part of the fourth lens group located on anobject side to be moved with a displacement component in a directionorthogonal to the optical axis, and satisfying the following conditionalexpressions:0.80<(−f4)/f5w<2.50FNw<3.300.30<fw/(−f4)<0.80FNt<4.20 where, f4 denotes a focal length of the fourth lens group, f5wdenotes a composite focal length of an optical system on an image sideincluding the fifth lens group in the wide angle end state, FNw denotesan F number of the whole system in the wide angle end state, FNt denotesan F number of the whole system in the telephoto end state, and fwdenotes a focal length of the whole system in the wide angle end state.19. A zoom optical system comprising in order from an object: a firstlens group having positive refractive power; a second lens group havingnegative refractive power; a third lens group having positive refractivepower; a fourth lens group having negative refractive power; and a fifthlens group having positive refractive power, wherein upon zooming from awide angle end state to a telephoto end state, the lens groups are movedalong an optical axis to change a distance between the first lens groupand the second lens group, a distance between the second lens group andthe third lens group, a distance between the third lens group and thefourth lens group, and a distance between the fourth lens group and thefifth lens group, the fifth lens group includes at least one positivelens and at least one negative lens, the second lens group is movedtoward the object along the optical axis upon focusing on a shortdistance object from an infinitely distant object, at least a part ofthe fourth lens group located on an object side is moved with adisplacement component in a direction orthogonal to the optical axis,and the following conditional expressions are satisfied:0.80<(−f4)/f5w<2.50FNw<3.300.30<fw/(−f4)<0.80FNt<4.20 where, f4 denotes a focal length of the fourth lens group, f5wdenotes a composite focal length of an optical system on an image sideincluding the fifth lens group in the wide angle end state, FNw denotesan F number of the whole system in the wide angle end state, FNt denotesan F number of the whole system in the telephoto end state, and fwdenotes a focal length of the whole system in the wide angle end state.20. The zoom optical system according to claim 19, wherein the followingconditional expression is satisfied:2.50<f1/f3<4.20 where, f1 denotes a focal length of the first lensgroup, and f3 denotes a focal length of the third lens group.
 21. Thezoom optical system according to claim 19, wherein the followingconditional expression is satisfied:0.25<f2/f4<0.55 where, f2 denotes a focal length of the second lensgroup.
 22. The zoom optical system according to claim 19, wherein thefollowing conditional expression is satisfied: 0.40<fw/f3<1.00 where, f3denotes a focal length of the third lens group.
 23. The zoom opticalsystem according to claim 19, wherein the following conditionalexpression is satisfied:2.00<ft/f3<5.00 where, f3 denotes a focal length of the third lensgroup, and ft denotes the focal length of the whole system in thetelephoto end state.